248 BOARD OF AGRICULTURE. 



down into the nodular phosphoric rocks of the basin, and yet 

 it would die for want of pliosphoric acid. The grand dis- 

 tinction, the only distinction, between soil fertility and soil 

 sterility, is not that there is not lime and potash and soda, and 

 phosphoric acid and magnesia, in endless quantities, in the 

 soil, but it is, that it is not soluble ; and the distinction, the 

 only distinction, between sterility and fertility, is solubility. 



But the more important question to us, gentlemen, is. How 

 can we make the materials for plant-growth contained in our 

 granite soil in countless quantities, available for the use of 

 plants? First, by the air. The air is a wonderful com- 

 pound. Of course we are so familiar with the air, that we 

 count it of little worth. It is, nevertheless, a most wonder- 

 ful mixture of certain important ingredients : First, oxygen ; 

 next, nitrogen, carbonic acid, ammonia, nitric acid, ozone. 

 That is your air. One of these elements, the gas oxygen, is 

 one of the most wonderful in the whole arcana of nature- 

 It is primarily the oxygen of the air which takes to pieces 

 and destroys every thing that we know. All the monuments 

 of man of every kind and description, — of marble, of granite, 

 of iron, — this one simple gas in the air will sooner or later 

 take to pieces, and crumble to dust. No power of ours, no 

 skill of ours, will ever be able to resist its encroachments. 

 This is the leading element in the air. The air has weight. 

 I put it in that way for my purpose. The air has weight, and 

 it penetrates the soil by expansion and contraction. Under 

 the influence of daily changes of temperature the air enters 

 the soil, and is expelled from the soil day by day, carrying in 

 new quantities of the fertilizing elements and new quantities 

 of the oxygen. 



Now, let us see what is the result. The oxygen of the 

 air being carried into the soil oxidizes all the minerals or 

 metals contained in it which I have just been enumerating. 

 It finds calcium in the soil, and changes it to lime. It finds 

 magnesium in the soil, and changes it to magnesia. It finds 

 sodium in the soil, and changes it to soda. It finds iron, and 

 changes it to the oxide. All these hard, impervious, insolu- 

 ble materials are thus softened and made available under the 

 influence of oxygen. But that is not all. This oxygen finds 

 in the soil a particle of sulphur, unites with it, and j'ou liave 

 oil of vitriol in the soil. It finds nitrogen, and, meeting with 



